The present invention relates to Dirofilaria and Brugia ankyrin nucleic acid molecules, proteins encoded by such nucleic acid molecules, antibodies raised against such proteins, compounds capable of inhibiting the function of such proteins and methods to identify such inhibitors. The present invention also includes therapeutic compositions comprising such nucleic acid molecules, proteins, antibodies, and/or inhibitors, as well as their use to protect animals from diseases caused by parasitic helminths, such as heartworm disease, elephantiasis, and hydrocele.
Parasitic helminth infections in animals, including humans, are typically treated by chemical drugs. One disadvantage with chemical drugs is that they must be administered often. For example, dogs susceptible to heartworm are typically treated monthly. Repeated administration of drugs, however, often leads to the development of resistant helminth strains that no longer respond to treatment. Furthermore, many of the chemical drugs cause harmful side effects in the animals being treated, and as larger doses become required due to the build up of resistance, the side effects become even greater. Moreover, a number of drugs only treat symptoms of a parasitic disease but are unable to prevent infection by the parasitic helminth.
An alternative method to prevent parasitic helminth infection includes administering a vaccine against a parasitic helminth. Although many investigators have tried to develop vaccines based on specific antigens, it is well understood that the ability of an antigen to stimulate antibody production does not necessarily correlate with the ability of the antigen to stimulate an immune response capable of protecting an animal from infection, particularly in the case of parasitic helminths. Although a number of prominent antigens have been identified in several parasitic helminths, including in Dirofilaria and Brugia species, there is yet to be a commercially available vaccine developed for any parasitic helminth.
As an example of the complexity of parasitic helminths, the life cycle of D. immitis, the helminth that causes heartworm, includes a variety of life forms, each of which presents different targets, and challenges, for immunization. In a mosquito, D. immitis microfilariae go through two larval stages (L1 and L2) and become mature third stage larvae (L3), which can then be transmitted back to the dog when the mosquito takes a blood meal. In a dog, the L3 molt to the fourth larval stage (L4), and subsequently to the fifth stage, or immature adults. The immature adults migrate to the heart and pulmonary arteries, where they mature to adult heartworms. Adult heartworms are quite large and preferentially inhabit the heart and pulmonary arteries of an animal. Sexually mature adults, after mating, produce microfilariae which traverse capillary beds and circulate in the vascular system of the dog. In particular, heartworm is a major problem in dogs, which typically do not develop immunity upon infection (i.e., dogs can become reinfected even after being cured by chemotherapy). In addition, heartworm infection has been reported in cats, ferrets, and humans.
As such, there remains a need to identify efficacious compositions that protect animals against diseases caused by parasitic helminths such as D. immitis and B. malayi. Such compositions would preferably also protect animals from infection by such helminths.
The mechanisms and regulatory pathways involved in D. immitis migration and development are not clear. From infective L3 to mature adult, the nematode has to migrate and develop, with two molts, within its definitive host. It has been shown in the free living nematode, Caenorhabditis elegans (C. elegans), that the development of the larvae is regulated by environmental signals through chemosensory neurons. Blockage of signal transmission affects the development of the nematode (Bargmann, et al., 1991, Science, 251, 1243-1246). Many neuron-related genes have been identified in C. elegans. Mutations of the genes which control normal neuron function in C. elegans will not only affect the behavior of the nematode, but will also affect the development of the larvae and egg laying of mutated female worms. In parasitic nematodes, very little is known about mechanisms involved in the signal transmission and the developmental regulation of the parasites. However, host and tissue specificities in parasite infections suggest that parasitic nematodes might also need correct environmental signals for development.
Ankyrins are peripheral membrane proteins which have been found in erythrocyte, kidney and neuronal cells of mammals. Genes coding for three different mammalian ankyrins (ankyrinR, ankyrinB and ankyrinG) have been cloned AnkyrinR was originally identified as part of the erythrocyte membrane skeleton, and was recently also localized to the plasma membrane of a subpopulation of post mitotic neurons in rat brain (Lambert, et al., 1993, J. Neurosci., 13, 3725-3735). AnkyrinB is a developmentally regulated human brain protein which has two alternatively spliced isoforms with molecular masses of 220 kilodaltons (kD) and 440 kD (Kunimoto, et al., 1991, J. Cell Biology, 115, 1319-1331). AnkyrinG is a more recently isolated human gene that encodes two neural-specific ankyrin variants (480 kD and 270 kD), which have been localized to the axonal initial segment and node of Ranvier (Kordeli, et al., 1995, J. Biol. Chem., 270, 2352-2359). Studies on mammalian ankyrins indicate that ankyrins bind a variety of proteins which have functions involved with the anion exchanger (Drenckhahn, et al., 1988, Science, 230, 1287-1289), Na+/K+xe2x88x92ATPase, amiloride-sensitive sodium channel in kidney (Smith, et al., 1991, Proc. Natl. Acad. Sci. U.S.A., 88, 6971-6975), voltage dependent sodium channel of the brain and the neuromuscular junction (Srinivasan, et al., 1988, Nature, 15 333, 177-180), and nervous system cell adhesion molecules (Davis, et al., 1994, J. Biol. Chem., 269,27163-27166).
Analyses of mammalian ankyrins have revealed that these large proteins are divided into three functional domains. These include an N-terminal membrane-binding domain of about 89-95 kD, a spectrin-binding domain of about 62 kD, and a C-terminal regulatory domain of about 50-55 kD. The membrane-binding domain is primarily comprised of tandem repeats of about 33 amino acids each. This domain usually has about 22-24 copies of these repeats. The repeat units appear to function in binding to membrane proteins such as anion exchangers, sodium channels, and certain adhesion molecules. The spectrin-binding domain, as the name implies, functions in binding to the spectrin-based cytoskeleton of cells positioned inside the plasma membrane. Finally, the regulatory domain, which is the most variant domain among the different ankyrins that have been studied, appears to function in as a repressor and/or an activator of the protein-binding activities of the other two domains. Some of the variability seen in this domain among different ankyrin species appears to be the result of alternative splicing of nascent transcripts. For a review of ankyrin structure and function, see, for example, Bennett, 1992, J. Biol. Chem., 267, 8703-8706. Bennett, ibid., is herein incorporated by reference in its entirety.
An ankyrin gene (UNC-44) has also been identified in the free living nematode, C. elegans. Mutation of UNC-44 affects the development and function of the nervous system (Otsuka et al., 1995, J. Cell Biology, 129, 1081-1092). More recently, a cDNA encoding a 90-kilodalton (kD) neuronal protein, E1, which is reported to be an ankyrin-related protein, has been cloned from the filariid nematode, Onchocerca volvulus (O. volvulus), a human parasite. The cDNA was identified by using immuno-screening with antisera collected from putatively immune individuals from an endemic area of onchocerciasis. Localization studies by immunohistochemical assay indicated that the O. volvulus E1 native protein was localized to the nerve ring, the neuronal cell bodies, and the basal labyrinth within the extracellular clefts of the hypodermis in the adult nematode (Erttmann et al., 1996a, J. Biol. Chem., 271, 1645-1650). This 462-amino acid O. volvulus protein is reported to be full length.
The present invention relates to a novel product and a process to protect animals against parasitic helminth infection (e.g., prevent and/or treat such an infection). According to the present invention there are provided Dirofilaria and Brugia ankyrin proteins and mimetopes thereof; Dirofilaria and Brugia ankyrin nucleic acid molecules, including those that encode such proteins; antibodies raised against such ankyrin proteins (i.e., anti-Dirofilaria and anti-Brugia ankyrin antibodies); and compounds that inhibit the function of parasitic helminth ankyrins (i.e, inhibitory compounds).
The present invention also includes methods to obtain and/or identify such proteins, nucleic acid molecules, antibodies and inhibitory compounds. Also included in the present invention are therapeutic compositions comprising such proteins, nucleic acid molecules, antibodies, and/or inhibitory compounds, as well as use of such therapeutic compositions to protect animals from diseases caused by parasitic helminths.
One embodiment of the present invention is an isolated nucleic acid molecule that includes either a Dirofilaria ankyrin nucleic acid molecule, preferably a Dirofilaria immitis (D. immitis) ankyrin nucleic acid molecule, or a Brugia ankyrin nucleic acid molecule, preferably a Brugia malayi (B. malayi) ankyrin nucleic acid molecule. Such nucleic acid molecules are referred to as ankyrin nucleic acid molecules. A D. immitis ankyrin nucleic acid molecule preferably includes nucleic acid sequence SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:86, SEQ ID NO:87, SEQ ID NO:88, SEQ ID NO:89, SEQ ID NO:90, SEQ ID NO:91, SEQ ID NO:92, SEQ ID NO:93, SEQ ID NO:94, SEQ ID NO:95, SEQ ID NO:96, SEQ ID NO:97, SEQ ID NO:98, SEQ ID NO:99, SEQ ID NO:100, SEQ ID NO:101, SEQ ID NO:102, SEQ ID NO:103, SEQ ID NO:104, SEQ ID NO:105, SEQ ID NO:106, SEQ ID NO:107, SEQ ID NO:108, SEQ ID NO:110, SEQ ID NO:112, SEQ ID NO:114, SEQ ID NO:116, SEQ ID NO:118, SEQ ID NO:120, SEQ ID NO:122, SEQ ID NO:124, SEQ ID NO:126, SEQ ID NO:128, SEQ ID NO:130, SEQ ID NO:132, SEQ ID NO:134, SEQ ID NO:136; SEQ ID NO:138, SEQ ID NO:140, SEQ ID NO:141, SEQ ID NO:143, SEQ ID NO:144, and/or SEQ ID NO:146, and a B. malayi ankyrin nucleic acid molecule preferably includes nucleic acid sequence SEQ ID NO:37, SEQ ID NO:38, SEQ ID NO:40, and/or SEQ ID NO:41.
In one embodiment, a preferred D. immitis or B. malayi ankyrin nucleic acid molecule comprises a coding region of at least about 1500 nucleotides, preferably at least about 3000 nucleotides, even more preferably at least about 4500 nucleotides, which is capable of encoding an ankyrin protein of at least about 500 amino acids in length, preferably at least about 1000 amino acids in length, even more preferably at least about 1500 amino acids in length. In another embodiment, a preferred D. immitis or B. malayi ankyrin nucleic acid molecule comprises a full-length coding region which encodes a full-length ankyrin protein.
The present invention also relates to recombinant molecules, recombinant viruses and recombinant cells that include an isolated ankyrin nucleic acid molecule of the present invention. Also included are methods to produce such nucleic acid molecules, recombinant molecules, recombinant viruses and recombinant cells.
Another embodiment of the present invention includes either a Dirofilaria or a Brugia ankyrin protein, or a protein that includes a Dirofilaria or a Brugia ankyrin protein. Preferred ankyrin proteins include D. immitis ankyrin proteins or B. malayi ankyrin proteins. A preferred D. immitis ankyrin protein comprises amino acid sequence SEQ ID NO:2, SEQ ID NO:7, SEQ ID NO:12, SEQ ID NO:15, SEQ ID NO:20, SEQ ID NO:23, SEQ ID NO:28, SEQ ID NO:33, SEQ ID NO:139, SEQ ID NO:142, SEQ ID NO:145, SEQ ID NO:161, SEQ ID NO:162, SEQ ID NO:163, SEQ ID NO:165, SEQ ID NO:166, SEQ ID NO:167, SEQ ID NO:168, SEQ ID NO:169, SEQ ID NO:170, and/or SEQ ID NO:171, and a preferred B. malayi ankyrin protein comprises amino acid sequence SEQ ID NO:38.
In one embodiment, a preferred D. immitis or B. malayi ankyrin protein comprises an amino acid sequence of at least about in length, preferably at least about 1000 amino acids in length, even more preferably at least about 1500 amino acids in length. In another embodiment, a preferred D. immitis or B. malayi ankyrin protein comprises a full-length protein, i.e., a protein encoded by a full-length coding region.
The present invention also relates to: mimetopes of either Dirofilaria or Brugia ankyrin proteins, preferably to mimetopes of either D. immitis and B. malayi ankyrin proteins; isolated antibodies that selectively bind to either Dirofilaria or Brugia ankyrin proteins or mimetopes thereof; and inhibitors of Dirofilaria or Brugia ankyrin protein function. Also included are methods, including recombinant methods, to produce proteins, mimetopes, antibodies, and inhibitors of the present invention.
Yet another embodiment of the present invention is a therapeutic composition that is capable of protecting an animal from disease caused by a parasitic helminth. Such a therapeutic composition includes one or more of the following protective compounds: a Dirofilaria or a Brugia ankyrin protein or a mimetope thereof; an isolated Dirofilaria or Brugia ankyrin nucleic acid molecule; an isolated antibody that selectively binds to a Dirofilaria or a Brugia ankyrin protein; and/or a compound capable of inhibiting ankyrin function identified by its ability to inhibit either Dirofilaria or a Brugia ankyrin function. A preferred therapeutic composition of the present invention also includes an excipient, an adjuvant and/or a carrier. Preferred ankyrin nucleic acid molecule therapeutic compositions of the present invention include genetic vaccines, recombinant virus vaccines and recombinant cell vaccines. Also included in the present invention is a method to protect an animal from disease caused by a parasitic helminth, comprising the step of administering to the animal a therapeutic composition of the present invention.
The present invention provides for isolated Dirofilaria and Brugia ankyrin proteins, isolated Dirofilaria and Brugia ankyrin nucleic acid molecules, antibodies directed against Dirofilaria and Brugia ankyrin proteins, and compounds able to inhibit parasitic helminth ankyrin function (i.e., inhibitory compounds). As used herein, the terms isolated Dirofilaria ankyrin proteins, isolated Brugia ankyrin proteins, isolated Dirofilaria ankyrin nucleic acid molecules, and isolated Brugia ankyrin nucleic acid molecules refers to ankyrin proteins and ankyrin nucleic acid molecules derived from parasitic helminths of the genera Dirofilaria and Brugia and, as such, can be obtained from their natural source, or can be produced using, for example, recombinant nucleic acid technology or chemical synthesis. Also included in the present invention is the use of these proteins, nucleic acid molecules, antibodies, and inhibitory compounds as therapeutic compositions to protect animals from parasitic helminth diseases as well as in other applications, such as those disclosed below.
The biological functions of ankyrin-related proteins in filariid nematodes are not known. However, inhibiting normal functions of the nervous system in parasitic nematodes might cause neurons to become insensitive to exogenous signals and lead to defects in the development of the parasite. While not being bound by theory, the possible link between neuronal proteins and the development of parasitic nematodes indicates that neuronal proteins, such as ankyrins, could be potential candidates for the development of a vaccine against parasitic nematode infections.
Dirofilaria and Brugia ankyrin proteins and nucleic acid molecules of the present invention have utility because they represent novel targets for anti-parasite vaccines and drugs. The products and processes of the present invention are advantageous because they enable the inhibition of parasite developmental and migratory pathways that involve ankyrin. While not being bound by theory, it is believed that nematode ankyrin-like proteins might affect the development and function of the nematode nervous system, rendering neurons insensitive to exogenous signals involved in migration and development.
Isolation of D. immitis and B. malayi ankyrin nucleic acid molecules and proteins of the present invention was surprising even in view of the reported O. volvulus E1 nucleic acid molecule and protein disclosed by Erttmann, et al., 1996a, ibid., and the reported C. elegans UNC-44 nucleic acid molecule and protein disclosed by Otsuka, et al., ibid. As described in more detail in the Examples, it was very difficult to isolate D. immitis ankyrin nucleic acid molecules, despite the knowledge of these reported O. volvulus and C. elegans nucleic acid sequences. Moreover, Erttmann, et al., 1996b, Trop. Med. Int. Health, 1, 558-574, teaches away from a D. immitis analog of the O. volvulus E1 protein, in that the reference discloses that affinity-purified rabbit antibodies raised against the O. volvulus E1 protein do not react with D. immitis by immunohistochemical analysis (see Erttmann, et al., 1996b, ibid., Table 2).
Furthermore, isolated D. immitis and B. malayi ankyrin nucleic acid molecules and proteins of the present invention, and particularly D. immitis and B. malayi ankyrin nucleic acid molecules containing full-length coding regions and full-length D. immitis and B. malayi ankyrin proteins, are distinct from the O. volvulus E1 nucleic acid molecule and protein disclosed by Erttmann, et al., 1996a, ibid. For example, the inventors disclose herein a D. immitis ankyrin cDNA molecule of about 5503 nucleotides that encodes a full-length protein of about 1745 amino acids, and has a predicted size of about 191.7 kD. This nucleic acid molecule and protein are in dramatic contrast to the reported O. volvulus full-length E1 protein of 462 amino acids (the O. volvulus full-length E1 protein is only about 26% the size of the D. immitis full-length protein), and to the reported O. volvulus E1 full-length cDNA molecule of 2043 nucleotides encoding that protein (i.e. the O. volvulus full-length cDNA is only about 37% the size of the D. immitis full-length nucleic acid molecule). The B. malayi ankyrin nucleic acid molecule disclosed herein, encoding a non-full-length ankyrin protein, spans a region of the B. malayi ankyrin gene that has no similarity to the O. volvulus E1 nucleic acid molecule and protein, i.e., the B. malayi nucleic acid molecule disclosed herein is in a region 5xe2x80x2 to the region that would correspond to the O. volvulus E1 nucleic acid molecule and protein.
One embodiment of the present invention is an isolated protein that includes a Dirofilaria ankyrin protein or a Brugia ankyrin protein. It is to be noted that the term xe2x80x9caxe2x80x9d or xe2x80x9canxe2x80x9d entity refers to one or more of that entity; for example, a protein refers to one or more proteins or at least one protein. As such, the terms xe2x80x9caxe2x80x9d (or xe2x80x9canxe2x80x9d), xe2x80x9cone or morexe2x80x9d and xe2x80x9cat least onexe2x80x9d can be used interchangeably herein. It is also to be noted that the terms xe2x80x9ccomprisingxe2x80x9d, xe2x80x9cincludingxe2x80x9d, and xe2x80x9chavingxe2x80x9d can be used interchangeably. According to the present invention, an isolated, or biologically pure, protein, is a protein that has been removed from its natural milieu. As such, xe2x80x9cisolatedxe2x80x9d and xe2x80x9cbiologically purexe2x80x9d do not necessarily reflect the extent to which the protein has been purified. An isolated protein of the present invention can be obtained from its natural source, can be produced using recombinant DNA technology, or can be produced by chemical synthesis.
As used herein, an isolated ankyrin protein of the present invention (i.e., a Dirofilaria ankyrin protein or a Brugia ankyrin protein) can be a full-length protein or any homolog of such a protein. An isolated protein of the present invention, including a homolog, can be identified in a straight-forward manner by the protein""s ability to elicit an immune response against a Dirofilaria ankyrin protein or a Brugia ankyrin protein. Examples of Dirofilaria and Brugia ankyrin homologs include Dirofilaria and Brugia ankyrin proteins in which amino acids have been deleted (e.g., a truncated version of the protein, such as a peptide), inserted, inverted, substituted and/or derivatized (e.g., by glycosylation, phosphorylation, acetylation, myristoylation, prenylation, palmitoylation, amidation and/or addition of glycerophosphatidyl inositol) such that the homolog includes at least one epitope capable of eliciting an immune response against a Dirofilaria or Brugia ankyrin protein, and/or of binding to an antibody directed against a Dirofilaria or Brugia ankyrin protein. That is, when the homolog is administered to an animal as an immunogen, using techniques known to those skilled in the art, the animal will produce an immune response against at least one epitope of a natural Dirofilaria or Brugia ankyrin protein. The ability of a protein to effect an immune response can be measured using techniques known to those skilled in the art. As used herein, the term xe2x80x9cepitopexe2x80x9d refers to the smallest portion of a protein or other antigen capable of selectively binding to the antigen binding site of an antibody or a T-cell receptor. It is well accepted by those skilled in the art that the minimal size of a protein epitope is about six to seven amino acids.
Dirofilaria and Brugia ankyrin protein homologs can be the result of natural allelic variation or natural mutation. Dirofilaria and Brugia ankyrin protein homologs of the present invention can also be produced using techniques known in the art including, but not limited to, direct modifications to the protein or modifications to the gene encoding the protein using, for example, classic or recombinant DNA techniques to effect random or targeted mutagenesis.
Ankyrin proteins of the present invention are encoded by Dirofilaria ankyrin nucleic acid molecules or Brugia ankyrin nucleic acid molecules. As used herein, a Dirofilaria or Brugia ankyrin nucleic acid molecule includes nucleic acid sequences related to a natural Dirofilaria or Brugia ankyrin gene, and preferably, to a D. immitis or a B. malayi ankyrin gene. As used herein, a Dirofilaria or Brugia ankyrin gene includes all regions such as regulatory regions that control production of the Dirofilaria or Brugia ankyrin protein encoded by the gene (such as, but not limited to, transcription, translation or post-translation control regions) as well as the coding region itself, and any introns or non-translated coding regions. As used herein, a gene that xe2x80x9cincludesxe2x80x9d or xe2x80x9ccomprisesxe2x80x9d a sequence may include that sequence in one contiguous array, or may include the sequence as fragmented exons. As used herein, the term xe2x80x9ccoding regionxe2x80x9d refers to a continuous linear array of nucleotides that translates into a protein. A full-length coding region is that coding region that is translated into a full-length, i.e., a complete protein as would be initially translated in its natural millieu, prior to any post-translational modifications. In one embodiment, a D. immitis ankyrin gene of the present invention includes the nucleic acid sequence SEQ ID NO:32, as well as the complement of SEQ ID NO:32. Nucleic acid sequence SEQ ID NO:32 represents the deduced sequence of the coding strand of a cDNA (complementary DNA) denoted herein as D. immitis ankyrin nucleic acid molecule nDiAnk5503, the production of which is disclosed in the Examples. Nucleic acid molecule nDiAnk5503 comprises an apparently full-length coding region. The complement of SEQ ID NO:32 (represented herein by SEQ ID NO:34) refers to the nucleic acid sequence of the strand complementary to the strand having SEQ ID NO:32, which can easily be determined by those skilled in the art. Likewise, a nucleic acid sequence complement of any nucleic acid sequence of the present invention refers to the nucleic acid sequence of the nucleic acid strand that is complementary to (i.e., can form a double helix with) the strand for which the sequence is cited. It should be noted that since nucleic acid sequencing technology is not entirely error-free, SEQ ID NO:32 (as well as other nucleic acid and protein sequences presented herein) represents an apparent nucleic acid sequence of the nucleic acid molecule encoding a D. immitis ankyrin protein of the present invention.
In another embodiment, a D. immitis ankyrin gene or nucleic acid molecule can be an allelic variant that includes a similar but not identical sequence to SEQ ID NO:32, SEQ ID NO:34, or any other D. immitis nucleic acid sequence cited herein. An allelic variant of a D. immitis ankyrin gene including SEQ ID NO:32 and SEQ ID NO:34, is a gene that occurs at essentially the same locus (or loci) in the genome as the gene including SEQ ID NO:32 and SEQ ID NO:34, but which, due to natural variations caused by, for example, mutation or recombination, has a similar but not identical sequence. Because natural selection typically selects against alterations that affect function, allelic variants usually encode proteins having similar activity to that of the protein encoded by the gene to which they are being compared. Allelic variants of genes or nucleic acid molecules can also comprise alterations in the 5xe2x80x2 or 3xe2x80x2 untranslated regions of the gene (e.g., in regulatory control regions), or can involve alternative splicing of a nascent transcript, thereby bringing alternative exons into juxtaposition. Similarly, a B. malayi ankyrin gene or nucleic acid molecule can be an allelic variant that includes a similar but not identical sequence to SEQ ID NO:37 and SEQ ID NO:39. Allelic variants are well known to those skilled in the art and would be expected to be found within a given parasitic helminth such as Dirofilaria or Brugia, since the respective genomes are diploid, and sexual reproduction will result in the reassortment of alleles.
The minimal size of an ankyrin protein homolog of the present invention is a size sufficient to be encoded by a nucleic acid molecule capable of forming a stable hybrid (i.e., hybridize under stringent hybridization conditions) with the complementary sequence of a nucleic acid molecule encoding the corresponding natural protein. As used herein, xe2x80x9cstringent hybridization conditionsxe2x80x9d refer to those experimental conditions under which nucleic acid molecules having similar nucleic acid sequences will anneal to each other. Stringent hybridization conditions typically permit the hybridization of nucleic acid molecules having at least about 70% nucleic acid sequence identity with the nucleic acid molecule being used as a probe in the hybridization reaction. Formulae to calculate the appropriate hybridization and wash conditions to achieve hybridization permitting 30% or less mis-match between two nucleic acid molecules are disclosed, for example, in Meinkoth et al., 1984, Anal. Biochem 138, 267-284. Meinkoth et al., ibid, is by reference herein in its entirety. As such, the size of the nucleic acid molecule encoding such a protein homolog is dependent on nucleic acid composition and percent homology between the nucleic acid molecule and complementary sequence. It should also be noted that the extent of homology required to form a stable hybrid can vary depending on whether the homologous sequences are interspersed throughout the nucleic acid molecules or are clustered (i.e., localized) in distinct regions on the nucleic acid molecules. The minimal size of such nucleic acid molecules is typically at least about 12 to about 15 nucleotides in length if the nucleic acid molecules are GC-rich and at least about 15 to about 17 bases in length if they are AT-rich. As such, the minimal size of a nucleic acid molecule used to encode an ankyrin protein homolog of the present invention is from about 12 to about 18 nucleotides in length. Thus, the minimal size of an ankyrin protein homolog of the present invention is from about 4 to about 6 amino acids in length. There is no limit, other than a practical limit, on the maximal size of such a nucleic acid molecule in that the nucleic acid molecule can include a portion of a gene, an entire gene, or multiple genes, or portions thereof. The preferred size of a protein encoded by a nucleic acid molecule of the present invention depends on whether a full-length, fusion, multivalent, or functional portion of such a protein is desired.
A preferred Dirofilaria or Brugia ankyrin protein of the present invention is a compound that when administered to an animal in an effective manner, is capable of protecting that animal from disease caused by a parasitic helminth. In accordance with the present invention, the ability of an ankyrin protein of the present invention to protect an animal from disease by a parasitic helminth refers to the ability of that protein to, for example, treat, ameliorate and/or prevent disease caused by parasitic helminths. In one embodiment, a Dirofilaria or Brugia ankyrin protein of the present invention can elicit an immune response (including a humoral and/or cellular immune response) against a parasitic helminth.
Suitable parasites to target include any parasite that is essentially incapable of causing disease in an animal administered a Dirofilaria or Brugia ankyrin protein of the present invention. As such, parasites to target includes any parasite that produces a protein having one or more epitopes that can be targeted by a humoral and/or cellular immune response against a Dirofilaria or Brugia ankyrin protein of the present invention and/or that can be targeted by an inhibitory compound that otherwise inhibits ankyrin function (e.g., a compound that binds to ankyrin thereby blocking parasite development and/or migration regulatory pathways), thereby resulting in the decreased ability of the parasite to cause disease in an animal. Preferred parasitic helminths to target include nematodes, cestodes, and trematodes, with nematodes being preferred. Preferred nematodes to target include filariid, ascarid, capillarid, strongylid, strongyloides, trichostrongyle, and trichurid nematodes. Particularly preferred nematodes are those of the genera Acanthocheilonema, Aelurostrongylus, Ancylostoma, Angiostrongylus, Ascaris, Brugia, Bunostomum, Capillaria, Chabertia, Cooperia, Crenosoma, Dictyocaulus, Dioctophyme, Dipetalonema, Diphyllobothrium, Diplydium, Dirofilaria, Dracunculus, Enterobius, Filaroides, Haemonchus, Lagochilascaris, Loa, Mansonella, Muellerius, Nanophyetus, Necator, Nematodirus, Oesophagostomum, Onchocerca, Opisthorchis, Ostertagia, Parafilaria, Paragonimus, Parascaris, Physaloptera, Protostrongylus, Setaria, Spirocerca, Spirometra, Stephanofilaria, Strongyloides, Strongylus, Thelazia, Toxascaris, Toxocara, Trichinella, Trichostrongylus, Trichuris. Uncinaria, and Wuchereria. Preferred filariid nematodes include Dirofilaria, Onchocerca, Acanthocheilonema, Brugia, Dipetalonema, Loa, Parafilaria, Setaria, Stephanofilaria and Wuchereria filariid nematodes, with D. immitis and B. malayi being even more preferred.
The present invention also includes mimetopes of Dirofilaria and Brugia ankyrin proteins of the present invention. As used herein, a mimetope of a Dirofilaria or Brugia ankyrin protein of the present invention refers to any compound that is able to mimic the activity of such an ankyrin protein, often because the mimetope has a structure that mimics the particular ankyrin protein. Mimetopes can be, but are not limited to: peptides that have been modified to decrease their susceptibility to degradation such as all-D retro peptides; anti-idiotypic and/or catalytic antibodies, or fragments thereof; non-proteinaceous immunogenic portions of an isolated protein (e.g., carbohydrate structures); and synthetic or natural organic molecules, including nucleic acids. Such mimetopes can be designed using computer-generated structures of proteins of the present invention. Mimetopes can also be obtained by generating random samples of molecules, such as oligonucleotides, peptides or other organic molecules, and screening such samples by affinity chromatography techniques using the corresponding binding partner.
One embodiment of a Dirofilaria or Brugia ankyrin protein of the present invention is a fusion protein that includes a Dirofilaria or Brugia ankyrin protein-containing domain attached to one or more fusion segments. Suitable fusion segments for use with the present invention include, but are not limited to, segments that can: enhance a protein""s stability; act as an immunopotentiator to enhance an immune response against a Dirofilaria or Brugia ankyrin protein; and/or assist in purification of a Dirofilaria or Brugia ankyrin protein (e.g., by affinity chromatography). A suitable fusion segment can be a domain of any size that has the desired function (e.g., imparts increased stability, imparts increased immunogenicity to a protein, and/or simplifies purification of a protein). Fusion segments can be joined to amino and/or carboxyl termini of the Dirofilaria or Brugia ankyrin-containing domain of the protein and can be susceptible to cleavage in order to enable straight-forward recovery of a Dirofilaria or Brugia ankyrin protein. Fusion proteins are preferably produced by culturing a recombinant cell transformed with a fusion nucleic acid molecule that encodes a protein including the fusion segment attached to either the carboxyl and/or amino terminal end of a ankyrin-containing domain. Preferred fusion segments include a metal binding domain (e.g., a poly-histidine segment); an immunoglobulin binding domain (e.g., Protein A; Protein G; T cell; B cell; Fc receptor or complement protein antibody-binding domains); a sugar binding domain (e.g., a maltose binding domain); and/or a xe2x80x9ctagxe2x80x9d domain (e.g., at least a portion of xcex2-galactosidase, a strep tag peptide, a T7 tag peptide, a Flag(trademark) peptide, or other domains that can be purified using compounds that bind to the domain, such as monoclonal antibodies). More preferred fusion segments include metal binding domains, such as a poly-histidine segment; a maltose binding domain; a strep tag peptide, such as that available from Biometra in Tampa, Fla.; and an S10 peptide. Examples of particularly preferred fusion proteins of the present invention include PHIS-PDiANK352, PHIS-PDiANK422, PHIS-PDiANK288, PHIS-PDiANK864, PHISDiANK352, PHISDiANK422, and PHISDiANK288 production of which is disclosed herein.
In another embodiment, a Dirofilaria or Brugia ankyrin protein of the present invention also includes at least one additional protein segment that is capable of protecting an animal from one or more diseases. Such a multivalent protective protein can be produced by culturing a cell transformed with a nucleic acid molecule comprising two or more nucleic acid domains joined together in such a manner that the resulting nucleic acid molecule is expressed as a multivalent protective compound containing at least two protective compounds capable of protecting an animal from diseases caused, for example, by at least one infectious agent.
Examples of multivalent protective compounds include, but are not limited to, a Dirofilaria or Brugia ankyrin protein of the present invention attached to one or more compounds protective against one or more other infectious agents, particularly an agent that infects humans, cats, dogs, cattle and/or horses, such as, but not limited to: viruses (e.g., adenoviruses, caliciviruses, coronaviruses, distemper viruses, hepatitis viruses, herpesviruses, immunodeficiency viruses, infectious peritonitis viruses, leukemia viruses, oncogenic viruses, panleukopenia viruses, papilloma viruses, parainfluenza viruses, parvoviruses, rabies viruses, and reoviruses, as well as other cancer-causing or cancer-related viruses); bacteria (e.g., Actinomyces, Bacillus, Bacteroides, Bordetella, Bartonella, Borrelia, Brucella, Campylobacter, Capnocytophaga, Clostridium, Corynebacterium, Coxiella, Dermatophilus, Enterococcus, Ehrlichia, Escherichia, Francisella, Fusobacterium, Haemobartonella, Helicobacter, Klebsiella, L-form bacteria, Leptospira, Listeria, Mycobacteria, Mycoplasma, Neorickettsia, Nocardia, Pasteurella, Peptococcus, Peptostreptococcus, Proteus, Pseudomonas, Rickettsia, Rochalimaea, Salmonella, Shigella, Staphylococcus, Streptococcus, and Yersinia; fungi and fungal-related microorganisms (e.g., Absidia, Acremonium, Alternaria, Aspergillus, Basidiobolus, Bipolaris, Blastomyces, Candida, Chlamydia, Coccidioides, Conidiobolus, Cryptococcus, Curvalaria, Epidermophyton, Exophiala, Geotrichum, Histoplasma, Madurella, Malassezia, Microsporum, Moniliella, Mortierella, Mucor, Paecilomyces, Penicillium, Phialemonium, Phialophora, Prototheca, Pseudallescheria, Pseudomicrodochium, Pythium, Rhinosporidium, Rhizopus, Scolecobasidium, Sporothrix, Stemphylium, Trichophyton, Trichosporon, and Xylohypha; and other parasites (e.g., Babesia, Balantidium, Besnoitia, Cryptosporidium, Eimeria, Encephalitozoon, Entamoeba, Giardia, Hammondia, Hepatozoon, Isospora, Leishmania, Microsporidia, Neospora, Nosema, Pentatrichomonas, Plasmodium, Pneumocystis, Sarcocystis, Schistosoma, Theileria, Toxoplasma, and Trypanosoma, as well as helminth parasites, such as those disclosed herein). In one embodiment, a Dirofilaria or Brugia ankyrin protein of the present invention is attached to one or more additional compounds protective against heartworm disease, elephantiasis, or hydrocele. In another embodiment, one or more protective compounds, such as those listed above, can be included in a multivalent vaccine comprising a Dirofilaria or Brugia ankyrin protein of the present invention and one or more other protective molecules as separate compounds.
A preferred isolated protein of the present invention is a protein encoded by at least one of the following nucleic acid molecules: nDiAnk937, nDiAnk936, nDiAnk1029, nDiAnk810, nDiAnk600, nDiAnk1228, nDiAnk1227, nDiAnk573, nDiAnk911, nDiAnk909, nDiAnk1096, nDiAnk1044, nDiAnk5503, nDiAnk5235, nDiAnk1056, nDiAnk1266, nDiAnk864, nBmAnk908, and nBmAnk906, or allelic variants of any of these nucleic acid molecules. Another preferred isolated protein is encoded by a nucleic acid molecule the having nucleic acid sequence SEQ ID NO:1, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:9, SEQ ID NO:11, SEQ ID NO:14, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:22, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:35, SEQ ID NO:38, SEQ ID NO:40, SEQ ID NO:86, SEQ ID NO:88, SEQ ID NO:90, SEQ ID NO:92, SEQ ID NO:93, SEQ ID NO:94, SEQ ID NO:96, SEQ ID NO:98, SEQ ID NO:100, SEQ ID NO:102, SEQ ID NO:104, SEQ ID NO:106, SEQ ID NO:138, SEQ ID NO:141, and/or SEQ ID NO:144; or an allelic variant of such a nucleic acid molecule.
Translation of SEQ ID NO:1, the coding strand of nDiAnk937, yields a protein of about 312 amino acids, denoted herein as PDiAnk312, the amino acid sequence of which is presented in SEQ ID NO:2, assuming a first in-frame codon extending from nucleotide 1 to nucleotide 3 of SEQ ID NO:1. The coding region encoding PDiAnk312 is presented herein as nDiAnk936, which has the nucleotide sequence SEQ ID NO:4 (the coding strand) and SEQ ID NO:5 (the complementary strand).
Translation of SEQ ID NO:6, the coding strand of nDiAnk1029, yields a protein of about 270 amino acids, denoted herein as PDiAnk270, the amino acid sequence of which is presented in SEQ ID NO:7, assuming a first in-frame codon extending from nucleotide 2 to nucleotide 4 of SEQ ID NO:6, and a termination codon extending from nucleotide 812 to nucleotide 814 of SEQ ID NO:6. The coding region encoding PDiAnk270, not including the termination codon, is presented herein as nDiAnk810, which has the nucleotide sequence SEQ ID NO:9 (the coding strand) and SEQ ID NO:10 (the complementary strand). The 147 amino acid residues on the C-terminal end of PDiAnk312 lined up with 100% identity to the 147 amino acid residues on the N-terminal end of PDiAnk270. PDiAnk270 thus represents approximately 123 amino acids of new D. immitis ankyrin amino acid sequence. The presence of a termination codon and a poly-A tail on nDiAnk1029 indicates that nDiAnk1029 represents the authentic 3xe2x80x2 end of the D. immitis ankyrin messenger RNA that was reverse-transcribed into cDNA.
Translation of SEQ ID NO:11, the coding strand of nDiAnk600, yields a protein of about 200 amino acids, denoted herein as PDiAnk200, the amino acid sequence of which is presented in SEQ ID NO:12, assuming a first in-frame codon extending from nucleotide 1 to nucleotide 3 of SEQ ID NO:11. The 14 amino acid residues on the C-terminal end of PDiAnk200 lined up with 100% identity to the 14 amino acid residues on the N-terminal end of PDiAnk312. PDiAnk200 thus represents approximately 186 amino acids of new D. immitis ankyrin amino acid sequence.
Translation of SEQ ID NO:14, the coding strand of nDiAnk1228, yields a protein of about 409 amino acids, denoted herein as PDiAnk409, the amino acid sequence of which is presented in SEQ ID NO:15, assuming a first in-frame codon extending from nucleotide 1 to nucleotide 3 of SEQ ID NO:14. The coding region encoding PDiAnk409 is presented herein as nDiAnk1227, which has the nucleotide sequence SEQ ID NO:17 (the coding strand) and SEQ ID NO:18 (the complementary strand). The 32 amino acid residues on the C-terminal end of PDiAnk409 lined up with 100% identity to the 32 amino acid residues on the N-terminal end of PDiAnk200. PDiAnk409 thus represents about 377 amino acids of new D. immitis ankyrin amino acid sequence.
Translation of SEQ ID NO:19, the coding strand of nDiAnk573, yields a protein of about 191 amino acids, denoted herein as PDiAnk191, the amino acid sequence of which is presented in SEQ ID NO:20, assuming a first in-frame codon extending from nucleotide 1 to nucleotide 3 of SEQ ID NO:19. The 32 amino acid residues on the C-terminal end of PDiAnk≮lined up with 100% identity to the 32 amino acid residues on the N-terminal end of PDiAnk409. PDiAnk191 thus represents approximately 159 amino acids of new D. immitis ankyrin amino acid sequence.
Translation of SEQ ID NO:22, the coding strand of nDiAnk911, yields a protein of about 303 amino acids, denoted herein as PDiAnk303, the amino acid sequence of which is presented in SEQ ID NO:23, assuming a first in-frame codon extending from nucleotide 1 to nucleotide 3 of SEQ ID NO:22. The coding region encoding PDiAnk303 is presented herein as nDiAnk909, which has the nucleotide sequence SEQ ID NO:25 (the coding strand) and SEQ ID NO:26 (the complementary strand). The 54 amino acid residues on the C-terminal end of PDiAnk303 lined up with 100% identity to the 54 amino acid residues on the N-terminal end of the PDiAnk409. PDiAnk303 thus represents approximately 249 amino acids of new D. immitis ankyrin amino acid sequence.
Translation of SEQ ID NO:27, the coding strand of nDiAnk1096, yields a protein of about 348 amino acids, denoted herein as PDiAnk384, the amino acid sequence of which is presented in SEQ ID NO:28, assuming a start codon extending from nucleotide 51 to nucleotide 53 of SEQ ID NO:27. The nucleic acid molecule representing the coding region encoding PDiAnk348, denoted herein as nDiAnk1044, is presented herein as SEQ ID NO:30 (the coding strand) and SEQ ID NO:31 (the complementary strand). The about 9 amino acid residues on the C-terminal end of PDiAnk348, lined up with about 100% identity to the about 9 amino acid residues on the N-terminal end of the PDiAnk303. PDiAnk348 thus represents approximately 339 amino acids of new D. immitis ankyrin amino acid sequence.
Translation of SEQ ID NO:32, the coding strand of nDiAnk5503, yields a full-length polypeptide of about 1745 amino acids, denoted PDiAnk1745, assuming a start codon extending from nucleotide 51 through nucleotide 53 of SEQ ID NO:32, and a stop codon extending from nucleotide 5286 through nucleotide 5285 of SEQ ID NO:32. The resulting amino acid sequence is presented as SEQ ID NO:33. The coding region encoding PDiAnk1745, not including the termination codon, is denoted herein as nDiANK5235, and has the nucleotide sequence SEQ ID NO:35 (the coding strand) and SEQ ID NO:36 (the complementary strand). SEQ ID NO:35 is predicted to encode a protein with a molecular mass of about 191.7 kD and with a predicted pI of about 5.76, as calculated by the DNAsis program (available from Hitachi Software, San Bruno, Calif.).
A homology search of a non-redundant protein database was performed with SEQ ID NO:33, using the blastp program available through the BLAST(trademark) network of the National Center for Biotechnology Information (NCBI) (National Library of Medicine, National Institutes of Health, Baltimore, MD), available on the World Wide Web. This database includes SwissProt+PIR+SPupdate+GenPept+GPUpdate+PDB databases. The highest scoring match of the homology search at amino acid level was GenBank(trademark) accession number gi|1208874, a C. elegans ankyrin-like protein, to which SEQ ID NO:33 showed about 69% identity, spanning from about amino acid 1 through about amino acid 1745 of SEQ ID NO:33. The second highest highest scoring match of the homology search at amino acid level was GenBank(trademark) accession number gi|406288, a human brain ankyrin protein (variant I, AnkyrinB), to which SEQ ID NO:33 showed about 51% identity, spanning from about amino acid 1 through about amino acid 1745.
SEQ ID NO:33 was also compared with the protein sequence of the O. volvulus E1 protein as disclosed by Erttmann, et al., 1996a, ibid. A region of SEQ ID NO:33 spanning from about amino acid 1282 to about amino acid 1745 showed about 78% identity to the 462-amino acid O. volvulus E1 protein. At the nucleotide level, the cDNA encoding SEQ ID NO:33 (i.e., SEQ ID NO:32) was compared to the cDNA encoding the O. volvulus E1 protein. A region of SEQ ID NO:32 spanning from about nucleotide 3423 to about nucleotide 5474 showed about 88% nucleic acid identity to the cDNA encoding the O. volvulus E1 protein.
Translation of SEQ ID NO:37, the coding strand of nBmAnk908, yields a non-full-length polypeptide of about 302 amino acids, denoted PBmAnk302, assuming a first in-frame codon extending from nucleotide 1 through nucleotide 3 of SEQ ID NO:37. The resulting amino acid sequence is presented as SEQ ID NO:38. The coding region encoding PBmAnk302 is denoted herein as nBmANK906, and has the nucleotide sequence SEQ ID NO:40 (the coding strand) and SEQ ID NO:41 (the complementary strand).
A homology search of a non-redundant protein database was performed on SEQ ID NO:38 using the BLAST network. The homology spans from about amino acid 1 through amino acid 302 of SEQ ID NO:38. The highest scoring match of the homology search at amino acid level was GenBank accession number A57282, a C. elegans ankyrin-like protein, which was about 86% identical to SEQ ID NO:38 through a region extending from about amino acid 353 through about amino acid 654 of A57282.
The amino acid sequence of SEQ ID NO:38 was also compared to D. immitis ankyrin protein PDiAnk1745 (i.e. SEQ ID NO:33 of the present invention). PBmAnk302 had 95% identity to the region of SEQ ID NO:33 spanning from about amino acid 341 through about amino acid 642.
Preferred ankyrin proteins of the present invention include proteins that are at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, and even more preferably at least about 95% identical, and even more preferably at least about 98% identical to PdiAnk1745, PDiANK352, PDiANK422, or PDiANK288; or are at least about 90%, and preferably at least about 95%, identical to PBmAnk302. More preferred are ankyrin proteins comprising PDiAnk312, PDiAnk270, PDiAnk200, PDiAnk409, PDiAnk191, PDiAnk303, PDiAnk348, PDiAnk1745, PDiANK352, PdiANK422, PDiANK288 or PBmAnk302; and proteins encoded by allelic variants of a nucleic acid molecules encoding these proteins.
A preferred ankyrin protein of the present invention includes a protein having an amino acid sequence that are at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, and even more preferably at least about 95%, and even more preferably at least about 98% identical to SEQ ID NO:33, SEQ ID NO:138, SEQ ID NO:141, SEQ ID NO:144; or a protein having amino acid sequences that is at least about 90%, and preferably at least about 95% identical to SEQ ID NO:38. Another preferred ankyrin protein of the present invention includes a protein having an amino acid sequence that is at least about 75% identical to SEQ ID NO:33, an amino acid sequence that is at least about 90% identical to SEQ ID NO:38 an amino acid sequence that is at least about 85% identical to SEQ ID NO:139, an amino acid sequence that is at least about 95% identical to SEQ ID NO:142, an amino acid sequence that is at least about 75% identical to SEQ ID NO:145, an amino acid sequence that is at least about 75% identical to SEQ ID NO:161, an amino acid sequence that is at least about 85% identical to SEQ ID NO:162, an amino acid sequence that is at least about 85% identical to SEQ ID NO:163, an amino acid sequence that is at least about 90% identical to SEQ ID NO:165, an amino acid sequence that is at least about 75% identical to SEQ ID NO:166, an amino acid sequence that is at least about 90% identical to SEQ ID NO:167, an amino acid sequence that is at least about 80% identical to SEQ ID NO:168, an amino acid sequence that is at least about 95% identical to SEQ ID NO:169, an amino acid sequence that is at least about 75% identical to SEQ ID NO:170, or an amino acid sequence that is at least about 95% identical to SEQ ID NO:171. A more preferred are ankyrin protein comprises amino acid sequence SEQ ID NO:2, SEQ ID NO:7, SEQ ID NO:12, SEQ ID NO:15, SEQ ID NO:20, SEQ ID NO:23, SEQ ID NO:28, SEQ ID NO:33, SEQ ID NO:38, SEQ ID NO:139, SEQ ID NO:142, SEQ ID NO:145, SEQ ID NO:161, SEQ ID NO:162, SEQ ID NO:163, SEQ ID NO:165, SEQ ID NO:166, SEQ ID NO:167, SEQ ID NO:168, SEQ ID NO:169, SEQ ID NO:170, and/or SEQ ID NO:171; and an ankyrin protein encoded by an allelic variant of a nucleic acid molecule encoding an ankyrin protein having any one of these amino acid sequences.
Particularly preferred Dirofilaria ankyrin proteins of the present invention comprise amino acid sequence SEQ ID NO:33 (including, but not limited to, the proteins consisting of amino acid sequence SEQ ID NO:33, fusion proteins and multivalent proteins), and proteins encoded by allelic variants of nucleic acid molecules encoding proteins having amino acid sequence SEQ ID NO:33; and particularly preferred Brugia ankyrin proteins of the present invention comprise amino acid sequence SEQ ID NO:38 (including, but not limited to, the proteins consisting of SEQ ID NO:38, fusion proteins and multivalent proteins), and proteins encoded by allelic variants of nucleic acid molecules encoding proteins having amino acid sequence SEQ ID NO:38.
In one embodiment, a preferred D. immitis or B. malayi ankyrin protein of the present invention comprises an amino acid sequence of at least about 500 amino acids, preferably at least about 1000 amino acids, and even more preferably at least about 1500 amino acids. Within this embodiment, a preferred D. immitis ankyrin protein of the present invention has an amino acid sequence comprising at least a portion of SEQ ID NO:33. In another embodiment, a preferred D. immitis or B. malayi ankyrin protein comprises a full-length protein, i.e., a protein encoded by a full-length coding region. A particularly preferred apparently full-length ankyrin protein is PDiAnk1745.
Additional preferred ankyrin proteins of the present invention include proteins encoded by nucleic acid molecules comprising at least a portion of nDiAnk937, nDiAnk936, nDiAnk1029, nDiAnk810, nDiAnk600, nDiAnk1228, nDiAnk1227, nDiAnk573, nDiAnk911, nDiAnk909, nDiAnk1096, nDiAnk1044, nDiAnk5503, nDiAnk5235, nBmAnk908, nDiAnk1056, nDiAnk1266, nDiAnk864, and/or nBmAnk906, as well as ankyrin proteins encoded by allelic variants of these nucleic acid molecules.
Also preferred are ankyrin proteins encoded by nucleic acid molecules having nucleic acid sequences comprising at least a portion of SEQ ID NO:1, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:9, SEQ ID NO:11, SEQ ID NO:14, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:22, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:40, SEQ ID NO:86, SEQ ID NO:88, SEQ ID NO:90, SEQ ID NO:92, SEQ ID NO:94, SEQ ID NO:96, SEQ ID NO:98, SEQ ID NO:100, SEQ ID NO:102, SEQ ID NO:104, SEQ ID NO:106, SEQ ID NO:138, SEQ ID NO:141, and/or SEQ ID NO:144 as well as allelic variants of these nucleic acid molecules.
In another embodiment, a preferred Dirofilaria or Brugia ankyrin protein of the present invention is encoded by a nucleic acid molecule comprising at least about 1500 nucleotides, preferably at least about 3000 nucleotides and more preferably at least about 4500 nucleotides. Within this embodiment is an ankyrin protein encoded by at least a portion nDiAnk5503 or by an allelic variant of this nucleic acid molecule. In yet another embodiment, a preferred Dirofilaria or Brugia ankyrin protein of the present invention is encoded by a nucleic acid molecule comprising an apparently full-length ankyrin coding region, i.e., a nucleic acid molecule encoding an apparently full-length ankyrin protein.
Another embodiment of the present invention is an isolated nucleic acid molecule comprising either a Dirofilaria ankyrin nucleic acid molecule or a Brugia ankyrin nucleic acid molecule. The identifying characteristics of such nucleic acid molecules is heretofore described. A nucleic acid molecule of the present invention can include an isolated natural Dirofilaria or Brugia ankyrin gene or a homolog thereof, the latter of which is described in more detail below. A nucleic acid molecule of the present invention can include one or more regulatory regions, full-length or partial coding regions, or combinations thereof. The minimal size of a nucleic acid molecule of the present invention is a size sufficient to allow the formation of a stable hybrid (i.e., hybridization under stringent hybridization conditions) with the complementary sequence of another nucleic acid molecule. As such, the minimal size of an ankyrin nucleic acid molecule of the present invention is from about 12 to about 18 nucleotides in length. Preferred ankyrin nucleic acid molecules include D. immitis ankyrin nucleic acid molecules and B. malayi ankyrin nucleic acid molecules.
In accordance with the present invention, an isolated nucleic acid molecule is a nucleic acid molecule that has been removed from its natural milieu (i.e., that has been subjected to human manipulation) and can include DNA, RNA, or derivatives of either DNA or RNA. As such, xe2x80x9cisolatedxe2x80x9d does not reflect the extent to which the nucleic acid molecule has been purified. An isolated Dirofilaria or Brugia ankyrin nucleic acid molecule of the present invention can be isolated from its natural source or produced using recombinant DNA technology (e.g., polymerase chain reaction (PCR) amplification or cloning) or chemical synthesis. Isolated Dirofilaria or Brugia ankyrin nucleic acid molecules can include, for example, natural allelic variants and nucleic acid molecules modified by nucleotide insertions, deletions, substitutions, and/or inversions in a manner such that the modifications do not substantially interfere with the nucleic acid molecule""s ability to encode an ankyrin protein of the present invention.
A Dirofilaria or Brugia ankyrin nucleic acid molecule homolog can be produced using a number of methods known to those skilled in the art, see, for example, Sambrook et al., 1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Labs Press; Sambrook et al., ibid., is herein incorporated by reference in its entirety. For example, nucleic acid molecules can be modified using a variety of techniques including, but not limited to, classic mutagenesis and recombinant DNA techniques such as site-directed mutagenesis, chemical treatment, restriction enzyme cleavage, ligation of nucleic acid fragments, PCR amplification, synthesis of oligonucleotide mixtures and ligation of mixture groups to xe2x80x9cbuildxe2x80x9d a mixture of nucleic acid molecules, and combinations thereof. Nucleic acid molecule homologs can be selected by hybridization with a Dirofilaria or Brugia ankyrin nucleic acid molecule or by screening the function of a protein encoded by the nucleic acid molecule (e.g., ability to elicit an immune response against at least one epitope of a Dirofilaria or Brugia ankyrin protein).
An isolated nucleic acid molecule of the present invention can include a nucleic acid sequence that encodes at least one Dirofilaria or Brugia ankyrin protein of the present invention, examples of such proteins being disclosed herein. Although the phrase xe2x80x9cnucleic acid moleculexe2x80x9d primarily refers to the physical nucleic acid molecule and the phrase xe2x80x9cnucleic acid sequencexe2x80x9d primarily refers to the sequence of nucleotides on the nucleic acid molecule, the two phrases can be used interchangeably, especially with respect to a nucleic acid molecule, or a nucleic acid sequence, being capable of encoding a Dirofilaria or Brugia ankyrin protein.
A preferred nucleic acid molecule of the present invention, when administered to an animal, is capable of protecting that animal from disease caused by a parasitic helminth. As will be disclosed in more detail below, such a nucleic acid molecule can be, or encode, an antisense RNA, a molecule capable of triple helix formation, a ribozyme, or other nucleic acid-based drug compound. In additional embodiments, a nucleic acid molecule of the present invention can encode a protective protein (e.g., an ankyrin protein of the present invention), the nucleic acid molecule being delivered to the animal, for example, by direct injection (i.e, as a genetic vaccine) or in a vehicle such as a recombinant virus vaccine or a recombinant cell vaccine.
One embodiment of the present invention is an ankyrin nucleic acid molecule comprising all or part of nucleic acid molecules nDiAnk937, nDiAnk936, nDiAnk1029, nDiAnk810, nDiAnk600, nDiAnk1228, nDiAnk1227, nDiAnk573, nDiAnk911, nDiAnk909, nDiAnk1096, nDiAnk1044, nDiAnk5503, nDiAnk5235, nDiAnk1056, nDiAnk1266, nDiAnk864, nBmAnk908, or nBmAnk906, or allelic variants of these nucleic acid molecules. Another preferred nucleic acid molecule of the present invention includes at least a portion of nucleic acid sequence SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:35, SEQ ID NO:36, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:40, SEQ ID NO:41, SEQ ID NO:86, SEQ ID NO:87, SEQ ID NO:88, SEQ ID NO:89, SEQ ID NO:90, SEQ ID NO:91, SEQ ID NO:92, SEQ ID NO:93, SEQ ID NO:94, SEQ ID NO:95, SEQ ID NO:96, SEQ ID NO:97, SEQ ID NO:98, SEQ ID NO:99, SEQ ID NO:100, SEQ ID NO:101, SEQ ID NO:102, SEQ ID NO:103, SEQ ID NO:104, SEQ ID NO:105, SEQ ID NO:106, SEQ ID NO:107, SEQ ID NO:138, SEQ ID NO:141, and/or SEQ ID NO:144, as well as allelic variants of nucleic acid molecules having these nucleic acid sequences. Such nucleic acid molecules can include nucleotides in addition to those included in the SEQ ID NOs, such as, but not limited to, a full-length gene, a full-length coding region, a nucleic acid molecule encoding a fusion protein, or a nucleic acid molecule encoding a multivalent protective compound.
In one embodiment, an ankyrin nucleic acid molecule of the present invention encodes a protein that is at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, and even more preferably at least about 95% identical to PDiAnk1745; or is at least about 90%, and preferably at least about 95%, identical to PBmAnk302. Even more preferred is a nucleic acid molecule encoding PDiAnk312, PDiAnk270, PDiAnk200, PDiAnk409, PDiAnk191, PDiAnk303, PDiAnk348, PDiAnk1745, PBmAnk302, and/or an allelic variant of such a nucleic acid molecule.
In another embodiment, an ankyrin nucleic acid molecule of the present invention encodes a protein having an amino acid sequence that is at least about 75%, preferably at least about 80%, more preferably at least about 85%, even more preferably at least about 90%, and even more preferably at least about 95% identical to SEQ ID NO:33; or is at least about 90%, and preferably at least about 95%, identical to SEQ ID NO:38. The present invention also includes an ankyrin nucleic acid molecule encoding a protein having at least a portion of SEQ ID NO:2, SEQ ID NO:7, SEQ ID NO:12, SEQ ID NO:15, SEQ ID NO:20, SEQ ID NO:23, SEQ ID NO:28, SEQ ID NO:33 SEQ ID NO:38, SEQ ID NO:139, SEQ ID NO:142, SEQ ID NO:145, SEQ ID NO:161, SEQ ID NO:162, SEQ ID NO:163, SEQ ID NO:165, SEQ ID NO:166, SEQ ID NO:167, SEQ ID NO:168, SEQ ID NO:169, SEQ ID NO:170, and/or SEQ ID NO:171, as well as allelic variants of an ankyrin nucleic acid molecule encoding a protein having these sequences, including nucleic acid molecules that have been modified to accommodate codon usage properties of the cells in which such nucleic acid molecules are to be expressed.
In another embodiment, a preferred Dirofilaria or Brugia ankyrin nucleic acid molecule encodes an ankyrin protein comprising at least about 500 amino acids, preferably at least about 1000 amino acids, and more preferably at least about 1500 amino acids; i.e., an ankyrin nucleic acid molecule that comprises a contiguous ankyrin coding region of at least about 1500 nucleotides, preferably at least about 3000 nucleotides, and more preferably at least about 4500 nucleotides.
In yet another embodiment, a preferred Dirofilaria or Brugia ankyrin nucleic acid molecule of the present invention comprises an apparently full-length ankyrin coding region, i.e., the preferred nucleic acid molecule encodes an apparently full-length ankyrin protein.
Knowing the nucleic acid sequences of certain Dirofilaria or Brugia ankyrin nucleic acid molecules of the present invention allows one skilled in the art to, for example, (a) make copies of those nucleic acid molecules, (b) obtain nucleic acid molecules including at least a portion of such nucleic acid molecules (e.g., nucleic acid molecules including full-length genes, full-length coding regions, regulatory control sequences, truncated coding regions), and (c) obtain other Dirofilaria or Brugia ankyrin nucleic acid molecules. Such nucleic acid molecules can be obtained in a variety of ways including screening appropriate expression libraries with antibodies of the present invention, or amplifying genomic DNA; traditional cloning techniques using oligonucleotide probes of the present invention to screen appropriate libraries; and PCR amplification of appropriate libraries or DNA using oligonucleotide primers of the present invention. Preferred libraries to screen or from which to amplify nucleic acid molecules include Dirofilaria or Brugia L3, L4 or adult cDNA libraries as well as genomic DNA libraries. Similarly, preferred DNA sources from which to amplify nucleic acid molecules include Dirofilaria or Brugia L3, L4 or adult cDNA and genomic DNA. Techniques to clone and amplify genes are disclosed, for example, in Sambrook et al., ibid.
The present invention also includes nucleic acid molecules that are oligonucleotides capable of hybridizing, under stringent hybridization conditions, with complementary regions of other, preferably longer, nucleic acid molecules of the present invention such as those comprising Dirofilaria or Brugia ankyrin nucleic acid molecules or other parasitic helminth ankyrin nucleic acid molecules. Oligonucleotides of the present invention can be RNA, DNA, or derivatives of either. The minimum size of such oligonucleotides is the size required for formation of a stable hybrid between an oligonucleotide and a complementary sequence on a nucleic acid molecule of the present invention. A preferred oligonucleotide of the present invention has a maximum size of about 100 nucleotides. The present invention includes oligonucleotides that can be used as, for example, probes to identify nucleic acid molecules, primers to produce nucleic acid molecules, or therapeutic reagents to inhibit Dirofilaria or Brugia ankyrin protein production or activity (e.g., as antisense-, triplex formation-, ribozyme- and/or RNA drug-based reagents). The present invention also includes the use of such oligonucleotides to protect animals from disease using one or more of such technologies. Appropriate oligonucleotide-containing therapeutic compositions can be administered to an animal using techniques known to those skilled in the art.
One embodiment of the present invention includes a recombinant vector, which includes at least one isolated nucleic acid molecule of the present invention, inserted into any vector capable of delivering the nucleic acid molecule into a host cell. Such a vector contains heterologous nucleic acid sequences, that is nucleic acid sequences that are not naturally found adjacent to nucleic acid molecules of the present invention and that preferably are derived from a species other than the species from which the nucleic acid molecule(s) are derived. The vector can be either RNA or DNA, either prokaryotic or eukaryotic, and typically is a virus or a plasmid. Recombinant vectors can be used in the cloning, sequencing, and/or otherwise manipulating of Dirofilaria and Brugia ankyrin nucleic acid molecules of the present invention.
One type of recombinant vector, referred to herein as a recombinant molecule, comprises a nucleic acid molecule of the present invention operatively linked to an expression vector. The phrase operatively linked refers to insertion of a nucleic acid molecule into an expression vector in a manner such that the molecule is able to be expressed when transformed into a host cell. As used herein, an expression vector is a DNA or RNA vector that is capable of transforming a host cell and of effecting expression of a specified nucleic acid molecule. Preferably, the expression vector is also capable of replicating within the host cell. Expression vectors can be either prokaryotic or eukaryotic, and are typically viruses or plasmids. Expression vectors of the present invention include any vectors that function (i.e., direct gene expression) in recombinant cells of the present invention, including in bacterial, fungal, parasite, insect, other animal, and plant cells. Preferred expression vectors of the present invention can direct gene expression in bacterial, yeast, helminth or other parasite, insect and mammalian cells, and more preferably in the cell types disclosed herein.
In particular, expression vectors of the present invention contain regulatory sequences such as transcription control sequences, translation control sequences, origins of replication, and other regulatory sequences that are compatible with the recombinant cell and that control the expression of nucleic acid molecules of the present invention. In particular, recombinant molecules of the present invention include transcription control sequences. Transcription control sequences are sequences which control the initiation, elongation, and termination of transcription. Particularly important transcription control sequences are those which control transcription initiation, such as promoter, enhancer, operator and repressor sequences. Suitable transcription control sequences include any transcription control sequence that can function in at least one of the recombinant cells of the present invention. A variety of such transcription control sequences are known to those skilled in the art. Preferred transcription control sequences include those which function in bacterial, yeast, helminth or other endoparasite, or insect and mammalian cells, such as, but not limited to, tac, lac, trp, trc, oxy-pro, omp/lpp, rrnB, bacteriophage lambda (such as lambda pL and lambda pR and fusions that include such promoters), bacteriophage T7, T7lac, bacteriophage T3, bacteriophage SP6, bacteriophage SP01, metallothionein, alpha-mating factor, Pichia alcohol oxidase, alphavirus subgenomic promoter, antibiotic resistance gene, baculovirus, Heliothis zea insect virus, vaccinia virus, herpesvirus, raccoon poxvirus, other poxvirus, adenovirus, cytomegalovirus (such as immediate early promoter), simian virus 40, retrovirus, actin, retroviral long terminal repeat, Rous sarcoma virus, heat shock, phosphate and nitrate transcription control sequences as well as other sequences capable of controlling gene expression in prokaryotic or eukaryotic cells. Additional suitable transcription control sequences include tissue-specific promoters and enhancers as well as lymphokine-inducible promoters (e.g., promoters inducible by interferons or interleukins). Transcription control sequences of the present invention can also include naturally occurring transcription control sequences naturally associated with parasitic helminths, such as D immitis or B. malayi transcription control sequences.
Suitable and preferred nucleic acid molecules to include in recombinant vectors of the present invention are as disclosed herein. Preferred nucleic acid molecules to include in recombinant vectors, and particularly in recombinant molecules, include nDiAnk937, nDiAnk936, nDiAnk1029, nDiAnk810, nDiAnk600, nDiAnk1228, nDiAnk1227, nDiAnk573, nDiAnk911, nDiAnk909, nDiAnk1096, nDiAnk1044, nDiAnk5503, nDiAnk5235, nDiAnk1056, nDiAnk1266, nDiAnk864, nBmAnk908, and nBmAnk906. Particularly preferred recombinant molecules of the present invention include pTrc-nDiAnk1866, pTrc-nDiAnk1056, pTrc-nDiAnk1266, pTrc-nDiAnk864, pTrc-nDiAnk1056, pTrc-nDiAnk1266, and pTrc-nDiAnk864, the production of which are described in the Examples section.
Recombinant molecules of the present invention may also (a) contain secretory signals (i.e., signal segment nucleic acid sequences) to enable an expressed parasitic helminth protein of the present invention to be secreted from the cell that produces the protein and/or (b) contain fusion sequences which lead to the expression of nucleic acid molecules of the present invention as fusion proteins. Examples of suitable signal segments include any signal segment capable of directing the secretion of a protein of the present invention. Preferred signal segments include, but are not limited to, tissue plasminogen activator (t-PA), interferon, interleukin, growth hormone, histocompatibility and viral envelope glycoprotein signal segments. Suitable fusion segments encoded by fusion segment nucleic acids are disclosed herein. In addition, a nucleic acid molecule of the present invention can be joined to a fusion segment that directs the encoded protein to the proteosome, such as a ubiquitin fusion segment. Eukaryotic recombinant molecules may also include intervening and/or untranslated sequences surrounding and/or within the nucleic acid sequences of nucleic acid molecules of the present invention.
Another embodiment of the present invention includes a recombinant cell comprising a host cell transformed with one or more recombinant molecules of the present invention. Transformation of a nucleic acid molecule into a cell can be accomplished by any method by which a nucleic acid molecule can be inserted into the cell. Transformation techniques include, but are not limited to, transfection, electroporation, microinjection, lipofection, adsorption, and protoplast fusion. A recombinant cell may remain unicellular or may grow into a tissue, organ or a multicellular organism. Transformed nucleic acid molecules of the present invention can remain extrachromosomal or can integrate into one or more sites within a chromosome of the transformed (i.e., recombinant) cell in such a manner that their ability to be expressed is retained. Preferred nucleic acid molecules with which to transform a cell include Dirofilaria and Brugia ankyrin nucleic acid molecules disclosed herein. Particularly preferred nucleic acid molecules with which to transform a cell include nDiAnk937, nDiAnk936, nDiAnk1029, nDiAnk810, nDiAnk600, nDiAnk1228, nDiAnk1227, nDiAnk573, nDiAnk911, nDiAnk909, nDiAnk1096, nDiAnk1044, nDiAnk5503, nDiAnk5235, nDiAnk1056, nDiAnk1266, nDiAnk864, nBmAnk908, and nBmAnk906.
Suitable host cells to transform include any cell that can be transformed with a nucleic acid molecule of the present invention. Host cells can be either untransformed cells or cells that are already transformed with at least one nucleic acid molecule (e.g., nucleic acid molecules encoding one or more proteins of the present invention and/or other proteins useful in the production of multivalent vaccines). Host cells of the present invention either can be endogenously (i.e., naturally) capable of producing Dirofilaria or Brugia ankyrin proteins of the present invention or can be capable of producing such proteins after being transformed with at least one nucleic acid molecule of the present invention. Host cells of the present invention can be any cell capable of producing at least one protein of the present invention, and include bacterial, fungal (including yeast), parasite (including helminth, protozoa and ectoparasite), other insect, other animal and plant cells. Preferred host cells include bacterial, mycobacterial, yeast, helminth, insect and mammalian cells. More preferred host cells include Salmonella, Escherichia, Bacillus, Listeria, Saccharomyces, Spodoptera, Mycobacteria, Trichoplusia, BHK (baby hamster kidney) cells, MDCK cells (Madin-Darby canine kidney cell line), CRFK cells (Crandell feline kidney cell line), CV-1 cells (African monkey kidney cell line used, for example, to culture raccoon poxvirus), COS (e.g., COS-7) cells, and Vero cells. Particularly preferred host cells are Escherichia coli, including E. coli K-12 derivatives; Salmonella typhi; Salmonella typhimurium, including attenuated strains such as UK-1 "khgr"3987 and SR-11 "khgr"4072; Spodoptera frugiperda; Trichoplusia ni; BHK cells; MDCK cells; CRFK cells; CV-1 cells; COS cells; Vero cells; and non-tumorigenic mouse myoblast G8 cells (e.g., ATCC CRL 1246). Additional appropriate mammalian cell hosts include other kidney cell lines, other fibroblast cell lines (e.g., human, murine or chicken embryo fibroblast cell lines), myeloma cell lines, Chinese hamster ovary cells, mouse NIH/3T3 cells, LMTK31 cells and/or HeLa cells. In one embodiment, the proteins may be expressed as heterologous proteins in myeloma cell lines employing immunoglobulin promoters.
A recombinant cell is preferably produced by transforming a host cell with one or more recombinant molecules, each comprising one or more nucleic acid molecules of the present invention operatively linked to an expression vector containing one or more transcription control sequences, examples of which are disclosed herein. Particularly preferred recombinant molecules include pTrc-nDiAnk1866, pTrc-nDiAnk1056, pTrc-nDiAnk1266, pTrc-nDiAnk864, pTrc-nDiAnk1056, pTrc-nDiAnk1266, and pTrc-nDiAnk864.
A recombinant cell of the present invention includes any cell transformed with at least one of any nucleic acid molecule of the present invention. Suitable and preferred nucleic acid molecules as well as suitable and preferred recombinant molecules with which to transfer cells are disclosed herein. Particularly preferred recombinant cells include E. coli:pTrc-nDiAnk1866, E. coli:pTrc-nDiAnk1056, E. coli:pTrc-nDiAnk1266, E. coli:pTrc-nDiAnk864, E. coli:pTrc-nDiAnk1056, E. coli:pTrc-nDiAnk1266, E. coli:pTrc-nDiAnk864. Details regarding the production of these recombinant cells are disclosed herein.
Recombinant cells of the present invention can also be co-transformed with one or more recombinant molecules including Dirofilaria or Brugia ankyrin nucleic acid molecules encoding one or more proteins of the present invention and one or more other nucleic acid molecules encoding other protective compounds, as disclosed herein (e.g., to produce multivalent vaccines).
Recombinant DNA technologies can be used to improve expression of transformed nucleic acid molecules by manipulating, for example, the number of copies of the nucleic acid molecules within a host cell, the efficiency with which those nucleic acid molecules are transcribed, the efficiency with which the resultant transcripts are translated, and the efficiency of post-translational modifications. Recombinant techniques useful for increasing the expression of nucleic acid molecules of the present invention include, but are not limited to, operatively linking nucleic acid molecules to high-copy number plasmids, integration of the nucleic acid molecules into one or more host cell chromosomes, addition of vector stability sequences to plasmids, substitutions or modifications of transcription control signals (e.g., promoters, operators, enhancers), substitutions or modifications of translational control signals (e.g., ribosome binding sites, Shine-Dalgarno sequences), modification of nucleic acid molecules of the present invention to correspond to the codon usage of the host cell, deletion of sequences that destabilize transcripts, and use of control signals that temporally separate recombinant cell growth from recombinant enzyme production during fermentation. The activity of an expressed recombinant protein of the present invention may be improved by fragmenting, modifying, or derivatizing nucleic acid molecules encoding such a protein.
Isolated Dirofilaria or Brugia ankyrin proteins of the present invention can be produced in a variety of ways, including production and recovery of natural proteins, production and recovery of recombinant proteins, and chemical synthesis of the proteins. In one embodiment, an isolated protein of the present invention is produced by culturing a cell capable of expressing the protein under conditions effective to produce the protein, and recovering the protein. A preferred cell to culture is a recombinant cell of the present invention. Effective culture conditions include, but are not limited to, effective media, bioreactor, temperature, pH and oxygen conditions that permit protein production. An effective, medium refers to any medium in which a cell is cultured to produce a Dirofilaria or Brugia ankyrin protein of the present invention. Such medium typically comprises an aqueous medium having assimilable carbon, nitrogen and phosphate sources, and appropriate salts, minerals, metals and other nutrients, such as vitamins. Cells of the present invention can be cultured in conventional fermentation bioreactors, shake flasks, test tubes, microtiter dishes, and petri plates. Culturing can be carried out at a temperature, pH and oxygen content appropriate for a recombinant cell. Such culturing conditions are within the expertise of one of ordinary skill in the art. Examples of suitable conditions are included in the Examples section.
Depending on the vector and host system used for production, resultant proteins of the present invention may either remain within the recombinant cell; be secreted into the fermentation medium; be secreted into a space between two cellular membranes, such as the periplasmic space in E. coli; or be retained on the outer surface of a cell or viral membrane.
The phrase xe2x80x9crecovering the proteinxe2x80x9d, as well as similar phrases, refers to collecting the whole fermentation medium containing the protein and need not imply additional steps of separation or purification. Proteins of the present invention can be purified using a variety of standard protein purification techniques, such as, but not limited to, affinity chromatography, ion exchange chromatography, filtration, electrophoresis, hydrophobic interaction chromatography, gel filtration chromatography, reverse phase chromatography, concanavalin A chromatography, chromatofocusing and differential solubilization. Proteins of the present invention are preferably retrieved in xe2x80x9csubstantially purexe2x80x9d form. As used herein, xe2x80x9csubstantially purexe2x80x9d refers to a purity that allows for the effective use of the protein as a therapeutic composition or diagnostic. A therapeutic composition for animals, for example, should exhibit no substantial toxicity and preferably should be capable of stimulating the production of antibodies in a treated animal.
The present invention also includes isolated (i.e., removed from their natural milieu) antibodies that selectively bind to a Dirofilaria or Brugia ankyrin protein of the present invention or a mimetope thereof (e.g., anti-Dirofilaria ankyrin antibodies or anti-Brugia ankyrin antibodies). As used herein, the term xe2x80x9cselectively binds toxe2x80x9d an ankyrin protein refers to the ability of antibodies of the present invention to preferentially bind to specified proteins and mimetopes thereof of the present invention. Binding can be measured using a variety of methods standard in the art including enzyme immunoassays (e.g., ELISA), immunoblot assays, etc.; see, for example, Sambrook et al., ibid., and Harlow, et al., 1988, Antibodies, a Laboratory Manual, Cold Spring Harbor Labs Press; Harlow et al., ibid., is herein incorporated by reference in its entirety. An anti-ankyrin antibody of the present invention preferably selectively binds to a Dirofilaria or Brugia ankyrin protein in such a way as to inhibit the function of that protein.
Isolated antibodies of the present invention can include antibodies in serum, or antibodies that have been purified to varying degrees. Antibodies of the present invention can be polyclonal or monoclonal, or can be functional equivalents such as antibody fragments and genetically-engineered antibodies, including single chain antibodies or chimeric antibodies that can bind to one or more epitopes.
A preferred method to produce antibodies of the present invention includes (a) administering to an animal an effective amount of a protein, peptide or mimetope thereof of the present invention to produce the antibodies and (b) recovering the antibodies. In another method, antibodies of the present invention are produced recombinantly using techniques as heretofore disclosed to produce ankyrin proteins of the present invention. Antibodies raised against defined proteins or mimetopes can be advantageous because such antibodies are not substantially contaminated with antibodies against other substances that might otherwise cause interference in a diagnostic assay or side effects if used in a therapeutic composition.
Antibodies of the present invention have a variety of potential uses that are within the scope of the present invention. For example, such antibodies can be used (a) as therapeutic compounds to passively immunize an animal in order to protect the animal from parasitic helminths susceptible to treatment by such antibodies, (b) as reagents in assays to detect infection by such helminths and/or (c) as tools to screen expression libraries and/or to recover desired proteins of the present invention from a mixture of proteins and other contaminants. Furthermore, antibodies of the present invention can be used to target cytotoxic agents to parasitic helminths in order to directly kill such helminths. Targeting can be accomplished by conjugating (i.e., stably joining) such antibodies to the cytotoxic agents using techniques known to those skilled in the art. Suitable cytotoxic agents are known to those skilled in the art.
One embodiment of the present invention is a therapeutic composition that, when administered to an animal in an effective manner, is capable of protecting that animal from disease caused by a parasitic helminth. Therapeutic compositions of the present invention include at least one of the following protective compounds: an isolated Dirofilaria or Brugia ankyrin protein or a mimetope thereof, an isolated Dirofilaria or Brugia ankyrin nucleic acid molecule, an isolated antibody that selectively binds to a Dirofilaria or Brugia ankyrin protein, an inhibitor of ankyrin function identified by its ability to bind to a Dirofilaria or Brugia ankyrin protein and thereby impede development and/or migration of the parasite, and a mixture thereof (i.e., combination of at least two of the compounds). As used herein, a protective compound refers to a compound that, when administered to an animal in an effective manner, is able to treat, ameliorate, and/or prevent disease caused by a parasitic helminth. Preferred helminths to target are heretofore disclosed. Examples of proteins, nucleic acid molecules, antibodies and inhibitors of the present invention are disclosed herein.
The present invention also includes a therapeutic composition comprising at least one Dirofilaria or Brugia ankyrin-based compound of the present invention in combination with at least one additional compound protective against one or more infectious agents. Examples of such compounds and infectious agents are disclosed herein.
Therapeutic compositions of the present invention can be administered to any animal susceptible to such therapy, preferably to mammals, and more preferably to dogs, cats, humans, ferrets, horses, cattle, sheep and other pets, economic food animals and/or zoo animals. Preferred animals to protect against heartworm disease include dogs, cats, humans and ferrets, with dogs and cats being particularly preferred. The preferred animals to protect against elephantiasis and hydrocele include humans.
In one embodiment, a therapeutic composition of the present invention can be administered to the vector in which the parasitic helminth develops, such as to a mosquito in order to prevent the spread of heartworm. Such administration could be oral or by developing transgenic vectors capable of producing at least one therapeutic composition of the present invention. In another embodiment, an insect vector, such as a mosquito, can ingest therapeutic compositions present in the blood of a host that has been administered a therapeutic composition of the present invention.
In order to protect an animal from disease caused by a parasitic helminth, a therapeutic composition of the present invention is administered to the animal in an effective manner such that the composition is capable of protecting that animal from a disease caused by a parasitic helminth. Therapeutic compositions of the present invention can be administered to animals prior to infection in order to prevent infection (i.e., as a preventative vaccine) and/or can be administered to animals after infection in order to treat disease caused by the parasitic helminth (i.e., as a therapeutic vaccine).
Therapeutic compositions of the present invention can be formulated in an excipient that the animal to be treated can tolerate. Examples of such excipients include water, saline, Ringer""s solution, dextrose solution, Hank""s solution, and other aqueous physiologically balanced salt solutions. Nonaqueous vehicles, such as fixed oils, sesame oil, ethyl oleate, or triglycerides may also be used. Other useful formulations include suspensions containing viscosity enhancing agents, such as sodium carboxymethylcellulose, sorbitol, or dextran. Excipients can also contain minor amounts of additives, such as substances that enhance isotonicity and chemical stability. Examples of buffers include phosphate buffer, bicarbonate buffer and Tris buffer, while examples of preservatives include thimerosal, m- or o-cresol, formalin and benzyl alcohol. Standard formulations can either be liquid injectables or solids which can be taken up in a suitable liquid as a suspension or solution for injection. Thus, in a non-liquid formulation, the excipient can comprise dextrose, human serum albumin, preservatives, etc., to which sterile water or saline can be added prior to administration.
In one embodiment of the present invention, a therapeutic composition can include an adjuvant. Adjuvants are agents that are capable of enhancing the immune response of an animal to a specific antigen. Suitable adjuvants include, but are not limited to, cytokines, chemokines, and compounds that induce the production of cytokines and chemokines (e.g., granulocyte macrophage colony stimulating factor (GM-CSF), granulocyte colony stimulating factor (G-CSF), macrophage colony stimulating factor (M-CSF), colony stimulating factor (CSF), erythropoietin (EPO), interleukin 2 (IL-2), interleukin-3 (IL-3), interleukin 4 (IL-4), interleukin 5 (IL-5), interleukin 6 (IL-6), interleukin 7 (IL-7), interleukin 8 (IL-8), interleukin 10 (IL-10), interleukin 12 (IL-12), interferon gamma, interferon gamma inducing factor I (IGIF), transforming growth factor beta, RANTES (regulated upon activation, normal T-cell expressed and presumably secreted), macrophage inflammatory proteins (e.g., MIP-1 alpha and MIP-1 beta), and Leishmania elongation initiating factor (LEIF)); bacterial components (e.g., endotoxins, in particular superantigens, exotoxins and cell wall components); aluminum-based salts; calcium-based salts; silica; polynucleotides; toxoids; serum proteins, viral coat proteins; block copolymer adjuvants (e.g., Hunter""s Titermax(trademark) adjuvant (Vaxcel(trademark), Inc. Norcross, Ga.), Ribi adjuvants (Ribi ImmunoChem Research, Inc., Hamilton, Mont.); and saponins and their derivatives (e.g., Quil A (Superfos Biosector A/S, Denmark). Protein adjuvants of the present invention can be delivered in the form of the protein themselves or of nucleic acid molecules encoding such proteins using the methods described herein.
In one embodiment of the present invention, a therapeutic composition can include a carrier. Carriers include compounds that increase the half-life of a therapeutic composition in the treated animal. Suitable carriers include, but are not limited to, polymeric controlled release vehicles, biodegradable implants, liposomes, bacteria, viruses, other cells, oils, esters, and glycols.
One embodiment of the present invention is a controlled release formulation that is capable of slowly releasing a composition of the present invention into an animal. As used herein, a controlled release formulation comprises a composition of the present invention in a controlled release vehicle. Suitable controlled release vehicles include, but are not limited to, biocompatible polymers, other polymeric matrices, capsules, microcapsules, microparticles, bolus preparations, osmotic pumps, diffusion devices, liposomes, lipospheres, and transdermal delivery systems. Other controlled release formulations of the present invention include liquids that, upon administration to an animal, form a solid or a gel in situ. Preferred controlled release formulations are biodegradable (i.e., bioerodible).
A preferred controlled release formulation of the present invention is capable of releasing a composition of the present invention into the blood of the treated animal at a constant rate sufficient to attain therapeutic dose levels of the composition to protect an animal from disease caused by parasitic helminths. The therapeutic composition is preferably released over a period of time ranging from about 1 to about 12 months. A controlled release formulation of the present invention is capable of effecting a treatment preferably for at least about 1 month, more preferably for at least about 3 months, even more preferably for at least about 6 months, even more preferably for at least about 9 months, and even more preferably for at least about 12 months.
Therapeutic compositions of the present invention can be administered to animals prior to infection in order to prevent infection and/or can be administered to animals after infection in order to treat disease caused by the parasitic helminth. For example, proteins, mimetopes thereof, and antibodies thereof can be used as immunotherapeutic agents. Acceptable protocols to administer therapeutic compositions in an effective manner include individual dose size, number of doses, frequency of dose administration, and mode of administration. Determination of such protocols can be accomplished by those skilled in the art. A suitable single dose is a dose that is capable of protecting an animal from disease when administered one or more times over a suitable time period. For example, a preferred single dose of a protein, mimetope or antibody therapeutic composition is from about 1 microgram (pg) to about 10 milligrams (mg) of the therapeutic composition per kilogram body weight of the animal. Booster vaccinations can be administered from about 2 weeks to several years after the original administration. Booster administrations preferably are administered when the immune response of the animal becomes insufficient to protect the animal from disease. A preferred administration schedule is one in which from about 10 xcexcg to about 1 mg of the therapeutic composition per kg body weight of the animal is administered from about one to about two times over a time period of from about 2 weeks to about 12 months. Modes of administration can include, but are not limited to, subcutaneous, intradermal, intravenous, intranasal, oral, transdermal and intramuscular routes.
According to one embodiment, a nucleic acid molecule of the present invention can be administered to an animal in a fashion to enable expression of that nucleic acid molecule into a protective protein or protective RNA (e.g., antisense RNA, ribozyme, triple helix forms or RNA drug) in the animal. Nucleic acid molecules can be delivered to an animal in a variety of methods including, but not limited to, (a) administering a naked (i.e., not packaged in a viral coat or cellular membrane) nucleic acid as a genetic vaccine (e.g., as naked DNA or RNA molecules, such as is taught, for example in Wolff et al., 1990, Science 247, 1465-1468) or (b) administering a nucleic acid molecule packaged as a recombinant virus vaccine or as a recombinant cell vaccine (i.e., the nucleic acid molecule is delivered by a viral or cellular vehicle).
A genetic (i.e., naked nucleic acid) vaccine of the present invention includes a nucleic acid molecule of the present invention and preferably includes a recombinant molecule of the present invention that preferably is replication, or otherwise amplification, competent. A genetic vaccine of the present invention can comprise one or more nucleic acid molecules of the present invention in the form of, for example, a dicistronic recombinant molecule. Preferred genetic vaccines include at least a portion of a viral genome (i.e., a viral vector). Preferred viral vectors include those based on alphaviruses, poxviruses, adenoviruses, herpesviruses, picornaviruses, and retroviruses, with those based on alphaviruses (such as sindbis or Semliki forest virus), species-specific herpesviruses and poxviruses being particularly preferred. Any suitable transcription control sequence can be used, including those disclosed as suitable for protein production. Particularly preferred transcription control sequences include cytomegalovirus immediate early (preferably in conjunction with Intron-A), Rous sarcoma virus long terminal repeat, and tissue-specific transcription control sequences, as well as transcription control sequences endogenous to viral vectors if viral vectors are used. The incorporation of a xe2x80x9cstrongxe2x80x9d polyadenylation signal is also preferred.
Genetic vaccines of the present invention can be administered in a variety of ways, with intramuscular, subcutaneous, intradermal, transdermal, intranasal and oral routes of administration being preferred. A preferred single dose of a genetic vaccine ranges from about 1 nanogram (ng) to about 600 xcexcg, depending on the route of administration and/or method of delivery, as can be determined by those skilled in the art. Suitable delivery methods include, for example, by injection, as drops, aerosolized and/or topically. Genetic vaccines of the present invention can be contained in an aqueous excipient (e.g., phosphate buffered saline) alone or in a carrier (e.g., lipid-based vehicles).
A recombinant virus vaccine of the present invention includes a recombinant molecule of the present invention that is packaged in a viral coat and that can be expressed in an animal after administration. Preferably, the recombinant molecule is packaging- or replication-deficient and/or encodes an attenuated virus. A number of recombinant viruses can be used, including, but not limited to, those based on alphaviruses, poxviruses, adenoviruses, herpesviruses, picornaviruses, and retroviruses. Preferred recombinant virus vaccines are those based on alphaviruses (such as Sindbis virus), raccoon poxviruses, species-specific herpesviruses and species-specific poxviruses. An example of methods to produce and use alphavirus recombinant virus vaccines are disclosed in PCT Publication No. WO 94/17813, by Xiong et al., published Aug. 18, 1994, which is herein incorporated by reference in its entirety.
When administered to an animal, a recombinant virus vaccine of the present invention infects cells within the immunized animal and directs the production of a protective protein or RNA nucleic acid molecule that is capable of protecting the animal from disease caused by a parasitic helminth as disclosed herein. For example, a recombinant virus vaccine comprising an ankyrin nucleic acid molecule of the present invention is administered according to a protocol that results in the animal producing a sufficient immune response to protect itself from heartworm. A preferred single dose of a recombinant virus vaccine of the present invention is from about 1xc3x97104 to about 1xc3x97108 virus plaque forming units (pfu) per kilogram body weight of the animal. Administration protocols are similar to those described herein for protein-based vaccines, with subcutaneous, intramuscular, intranasal and oral administration routes being preferred.
A recombinant cell vaccine of the present invention includes recombinant cells of the present invention that express at least one protein of the present invention. Preferred recombinant cells for this embodiment include Salmonella, E. coli, Listeria, Mycobacterium, S. frugiperda, yeast, (including Saccharomyces cerevisiae and Pichia pastoris), BHK, CV-1, myoblast G8, COS (e.g., COS-7), Vero, MDCK and CRFK recombinant cells. Recombinant cell vaccines of the present invention can be administered in a variety of ways but have the advantage that they can be administered orally, preferably at doses ranging from about 108 to about 1012 cells per kilogram body weight. Administration protocols are similar to those described herein for protein-based vaccines. Recombinant cell vaccines can comprise whole cells, cells stripped of cell walls or cell lysates.
The efficacy of a therapeutic composition of the present invention to protect an animal from disease caused by a parasitic helminth can be tested in a variety of ways including, but not limited to, detection of protective antibodies (using, for example, proteins or mimetopes of the present invention), detection of cellular immunity within the treated animal, or challenge of the treated animal with the parasitic helminth to determine whether the treated animal is resistant to disease. Challenge studies can include implantation of chambers including parasitic helminth larvae into the treated animal and/or direct administration of larvae to the treated animal. In one embodiment, therapeutic compositions can be tested in animal models such as mice. Such techniques are known to those skilled in the art.
One preferred embodiment of the present invention is the use of Dirofilaria or Brugia ankyrin proteins, nucleic acid molecules, antibodies and inhibitors of the present invention, to protect an animal from heartworm. It is particularly preferred to prevent L3 that are delivered to the animal by the mosquito intermediate host from migrating from the site of inoculation and/or maturing into adult worms. As such, preferred therapeutic compositions are those that are able to inhibit at least one step in the portion of the parasite""s development cycle that includes L3, third molt, L4, fourth molt, immature adult prior to entering the circulatory system. In dogs, this portion of the development cycle is about 70 days. Particularly preferred therapeutic compositions include D. immitis ankyrin-based therapeutic compositions of the present invention. Such compositions include D. immitis ankyrin nucleic acid molecules, D. immitis ankyrin proteins and mimetopes thereof, anti-D. immitis ankyrin antibodies, and inhibitors of D. immitis ankyrin function. Therapeutic compositions are administered to animals in a manner effective to protect the animals from heartworm. Additional protection may be obtained by administering additional protective compounds, including other parasitic helminth proteins, nucleic acid molecules, antibodies and inhibitory compounds, as disclosed herein.
One therapeutic composition of the present invention includes an inhibitor of Dirofilaria or Brugia ankyrin function, i.e., a compound capable of substantially interfering with the function of a Dirofilaria or Brugia ankyrin protein susceptible to inhibition. For example, an isolated protein or mimetope thereof is administered in an amount and manner that elicits (i.e., stimulates) an immune response that is sufficient, upon interaction with a native ankyrin protein, to protect the animal from the disease. Similarly, an antibody of the present invention, when administered to an animal in an effective manner, is administered in an amount so as to be present in the animal at a titer that is sufficient, upon interaction of that antibody with a native ankyrin protein, to protect the animal from the disease, at least temporarily. Oligonucleotide nucleic acid molecules of the present invention can also be administered in an effective manner, thereby reducing expression of Dirofilaria or Brugia ankyrin proteins in order to interfere with development of parasitic helminths targeted in accordance with the present invention. Methods to identify certain functions, i.e., protein-binding capabilities, of Dirofilaria or Brugia ankyrin proteins of the present invention are disclosed herein.
One embodiment of the present invention is a method to identify proteins that specifically interact with an ankyrin protein of the present invention. The method can comprise the steps of a) identifying and isolating a protein-binding domain of an isolated Dirofilaria or Brugia ankyrin protein; b) contacting that protein-binding domain with isolated parasitic helminth proteins under conditions such that a parasitic helminth protein and the protein-binding domain can selectively interact and/or bind to each other, using, for example, the yeast two-hybrid system see, for example, Luban, et al., 1995, Curr. Opin. Biotechnol., 6, 59-64; and c) identifying those proteins that specifically bind to the isolated ankyrin protein-binding domain. Additional methods to identify protein-protein interactions with the protein-binding domains of an isolated ankyrin protein of the present invention are known to those skilled in the art. Examples include Biacore(copyright) screening, confocal immunofluorescent microscopy, and immunoprecipitations.
An inhibitor of ankyrin function can be identified using Dirofilaria or Brugia ankyrin proteins of the present invention. One embodiment of the present invention is a method to identify a compound capable of inhibiting ankyrin function of a parasitic helminth. Such a method includes the steps of: (a) identifying a protein binding or regulatory activity of an isolated ankyrin protein in vitro; (b) identifying a putative compound capable of binding to and/or inhibiting the identified protein binding or regulatory activity of the isolated ankyrin protein; (c) contacting D. immitis L3 larvae with the putative inhibitory compound under conditions in which, in the absence of the compound, the larvae are able to molt to the L4 stage; and (d) determining if the putative compound inhibits molting. Putative inhibitory compounds to screen include small organic molecules, antibodies (including mimetopes thereof), and ligand analogs. Such compounds are also screened to identify those that are substantially not toxic in host animals.
Inhibitors of ankyrin function identified by such a method can be tested for their ability to block development and/or migration of parasitic helminths, and particularly of D. immitis and B. malayi, in vivo. Preferred ankyrin proteins to inhibit are those produced by parasitic helminths, even more preferred ankyrin proteins to inhibit are those produced by filariid nematodes. A particularly preferred inhibitor of the present invention is capable of protecting an animal from heartworm disease, elephantiasis and/or hydrocele. It is also within the scope of the present invention to use inhibitors of the present invention to target diseases caused by parasitic helminths in animals. Compositions comprising inhibitors of ankyrin function can be administered to animals in an effective manner to protect animals from disease caused by parasitic helminths, and preferably to protect animals from heartworm disease, elephantiasis and/or hydrocele. Effective amounts and dosing regimens can be determined using techniques known to those skilled in the art.
It is also within the scope of the present invention to use isolated proteins, mimetopes, nucleic acid molecules and antibodies of the present invention as diagnostic reagents to detect infection by parasitic helminths. Such diagnostic reagents can be supplemented with additional compounds that can specifically detect all phases of the parasite""s life cycle. Methods to use such diagnostic reagents to diagnose parasitic helminth infection are well known to those skilled in the art. Suitable and preferred parasitic helminths to detect are those to which therapeutic compositions of the present invention are targeted. Particularly preferred parasitic helminths to detect using diagnostic reagents of the present invention are D. immitis and B. malayi.